Hi folks! I bought an '03 Jetta that had the Dieselgeek oil bypass filter installed(secondary). Being that it was installed at around 250k on engine I believe, is it worth it to keep it? Why I ask is that I'll be replacing valve cover in awhile due to leaks(already have new one) and the return port from DG filter is cobbled into the valve cover now w/ JBWeld it looks like,but doesn't leak, not sure If I'd be able to save the fitting when I do swap valve covers. Another question is the extra filter holds about a quart of oil-I changed it w/ last oil change, but supposed to last 20k-30k(maybe more). Do I have to remove filter and drain what I can and reinstall the used filter back on to get the most oil out of system so I don't add the dirty oil back into fresh oil? Seems to defeat purpose, and I sure as hell not going to spend anywhere from $30-$60 for another amsoil filter each change. I was thinking of just removing it and selling it, it's just a secondary car I'm using to not rack up miles on my '15 GSW as fast.....

Seriously, a solution looking for a problem. When you can disassemble a TDI engine at 400K miles and there is still evidence of cross hatching on the cylinder walls the stock oil filter and oil system must be doing something right.

I had an old Rambler that the oil filtration system from the factory that was of the bypass type. With those once the filter started getting dirty they would pretty much start to clog up. What they do is bypass pressure and volume away from componants the require full time lubrication.

Putting a bypass filter on a modern engine that already has 100% full oil filtration already is just plain absurd.For $180 for the setup and $41 each for the filters, the only thing the bypass filter is cleaning is your wallet.

Be strong! Don't become a member of the Amsoil cult. When Amsoil founder Albert J. Amatuzio "borrowed" synthetic oil technology from military aircraft in the 60's the benefits were a big deal, but nowadays all oil companies market synthetic oil.

The Amsoil bypass filter filters down to 2 microns, where the stock filter comes nowhere close. And I change the bypass filter every 100k, and it still has good flow (EaBP100). Any sooner and it's a waste of money. And with the bypass filtering the entire sump every 10 minutes or so, what's not to like.

I once did a UOA at about 10k on the oil, immediately post filter just to see how well it was performing. Analysis came back showing the sample was as clean as oil straight from a new bottle.

Fuel Economy: as good as 58 (over 700 miles) and as low as 30 over the same route

While there is cross hatching on the cylinders yet at high miles and it seems the oiled engine parts aren't what takes the car off the road (accidents, lack of maintenance, rust seem to do their part) I don't see a negative of having it either. It should keep the oil better, it helps with a little oil cooling and gives extra oil capacity along with the oil seems less cycles of wear due to more oil.

In the end it is personal preference. No harm or benefit really. Not like the K&N air filters which almost all can agree what they do.

I guess my biggest complaint is that if you don't drain the bypass filter, you still have a quart of used oil getting mixed in with the new oil, as I didn't see any drain valve on or around the bypass.

Since you are getting a new valve cover anyway just delete the bypass filter. Less hassle and expense during an oil change for an additional filter that essentially does nothing to prolong the service life of your engine.

A bypass filter routes some of the oil pumps volume back to the crankcase making less oil volume available where positive pressure lubrication is mandatory to prevent excessive wear on moving parts.